Does anyone know what movie this is?

okay so all I remeber is theres a boy and a girl there in a forest. There around 17 probbably. Theres a unicorn in it as well. I remeber the boy telling the girl to hide from some people. Sorry if thats not enough thats all I remeber. Its got to be a fantasy but I know nothing else. If it sounds familiar or you think you might know what it is please let me know!!! Sorry for all the typos and misspelling I'm doing this in ahurry.